4. Two 100-horsepower motors are under consideration by the Mighty Machinery Company. Motor Q costs $5,000 and operates at 90% efficiency. Motor R costs $3,500 and s 88% efficient. Annual operating and maintenance costs are estimated to be 15% of the initial purchase price. Power costs 3.2 cents per kilowatt-hour. How many hours of full-load operation are necessary each year in order to justify the purchase of motor Q? Use a 15-year planning horizon; assume that salvage values will equal 20% of the initial purchase price; and let the MARR be 15%. (Note: 0.746 kilowatts = 1 horsepower)